Method of making an upholstered body

ABSTRACT

An upholstered body, especially mattress and seat for automobiles, and method of making the same, according to which a core body of coil springs has a seamless cover of foamed material, for instance, of polyester, or polyether, around said core body.

llnited States Patent Field of Search ..29/9l,9l.1,9l.2

[151 3,660,876 Krier et al. [4 1 May 9, 11972 [54] METHOD OF MAKING AN 5 Ref Cited UPHOLSTERED BODY UNITED STATES PATENTS {72] inventors: Philipp Krier, Stuttgart-Schonberg; Lothar 3,090,154 5/1963 I Harris ..29/91.1 Fendler, Stuttgart, both of'Germany 3,142,515 7/1964 Wall et al ..297/452 3,258,511 6/1966 McGregor, Jr. ..264/45 [73] Assignee: .Mirabed AG., Zug, Switzerland Primary Examiner-John F. Campbell [22] Filed: Aug. 19, 1968 7 Assistant Examiner-R. J. Craig 2 AppL 753 391 Attorney-Walter Backer [30] Foreign Application Priority Data [57] ABSTRACT I An u bolstered bod es eciall mattress and seat for automo- A .l9,l967 G ..P1685176.6 P P Y ug ermany biles, and mthod 'of making the same, according to which a 52 U.S.C1 ..29 91,29/91.1,29 91.2 core d of Coil Springs has a Seamless Cover of foamed [51] Int. Cl ..B68g' 7/00 material, for instance, of p y 0r p y r n i core body.

5 Claims, 5 Drawing Figures PATENTEDMAY 91972 3, 860. 876

SHEET 1 BF 3 Fig./ I 1 lnven tars @QQE PATENTEDMAY 9 I972 SHKU 3 [1F 3 In ven Ions Zo/Jo EM,-

METHOD OF MAKING AN UPHOLSTERED BODY The present invention relates to a mattress and method of making the same, according to which a spring core is provided with a cover of foam material.

It is known to cover spring cores of mattresses with a twosectional hood of foam material, which hood is, prior to covering the spring core, cut so as to form a development and is then glued or cemented. This method has the drawback that it is awkward and expensive. Furthermore, the gluing areas of the cover offoam material are easily damaged.

' It is, therefore, an object of the present invention to provide a method of making a mattress which will assure a simple and complete cover of a spring core in a minimum of time.

It is anotherobject of this invention to provide a mattress and method of making the same, according to which in one working step with the application of the cover on the spring core, the cover is additionally provided with a coating, for instance, of textile material.

It is also an object of this invention to provide a mattress which can easily be reinforced at those areas which are particularly exposed to damage.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

FIG. Idiagrammatically illustrates a cross section through a mattress according to the invention.

FIG. 2 shows a section through a further embodiment of a mattress according to the invention.

FIG. 3 is a top view of a cutout portion of a spring core of a mattress according to the invention.

FIG. 4 is a perspective view of the springs shown in FIG. 1.

FIG. 5 illustrates, similar to FIG. 3, a further embodiment of a spring core according to the invention.

The method according to the present invention according to which a spring coreis covered with a cover of foam material, is characterized in that the prefabricated spring core in a foaming process is provided with a cover closed in itself of polyester, polyether, or a similar soft foam material. Due to the fact that the foam layer foams directly in the spring core and thus is shaped accordingly, the covering or coating of the spring core can be effected in a minimum of time. The spring core itself forms the inner form of the cover so that the latter will precisely fit. Furthermore, the cover prepared according to the invention is completely seamless so that even when being relatively thin it will have a considerable strength.

The method according to the invention can easily be practiced when the spring core, prior to the foaming of the layer of foam material is covered with textile material, synthetic material, or the like so that, at any rate, the layer of foam material will be prevented from passing between the springs or with a cover, for instance, of textile fabric, since such textile fabric cover enters'into an intimate connection with the foam material in such a way that the air entrapped in the spring core can escape during the foaming process. This air core will then, during the further foaming operation, produce a counter pressure against the foaming pressure. The thus formed air core is therefore during the manufacture of the mattress very advantageous during the foaming operation.

In certain instancesit is advantageous to provide the edges of the mattress with a reinforcement. This reinforcement may, in conformity with a further feature of the invention, be applied in the form of a reinforcing fabric or the like which intimately combines with the soft foam. By means of this reinforcement, certain edges of the mattress may be designed in a simple manner as form retaining edges. Textile fabric, wire fabric, fabric of synthetic material, wood or metal parts, are particularly suitable for this reinforcement.

According to a further feature of the present invention, a coating layer for the spring core, for instance, a textile fabric, is inserted in the foaming mold, and the spring core is, in said mold, covered with the soft foam layer so that the coating layer firmly combines-with the soft foam layer. In this way it is possible in a single operation to provide the spring core with the cover as well as with fabric material, for instance, cotton drill. The cover layer is, due to its fixed connection with the soft foam cover, prevented from slipping. Due to this cover, also the reinforcing areas are covered by the inserted fabric. In order to make possible that the covering layer is precisely in conformity with the foaming mold, said covering layer is pressed against the inner wall of the mold by gas under pressure. This gas filling is, advantageously, during the introduction of soft foam, withdrawn 'to the extent to which the soft foamisintroduced into the mold. p i

' According to still another feature of the invention, the soft foam layer is thicker or thinner at the side of the spring core than it is at the two large surfaces of the spring core. The spring core may have a height of 7.5 centimeters, and the soft foam layer at the top and bottom side may have a height of approximately 3 centimeters, while the soft foam layer at the sides may have a thickness of approximately 2 centimeters. The thinner side parts of the soft foam layer have a higher weight per volume during the foaming operation and thereby become stiffer so that a laterial stiffening, and consequently an increase in the form stability will be assured.

Referring now to the drawings in detail, a spring core 24 (FIG. 1) is provided with a cover 25 which may be formed, for instance, by an envelope of nettle cloth, jute, or the like. The thus formed spring core 24 is placed in a foaming mold 26 which comprises two mold sections 27 and 28. Between the inner surface of the foaming mold 26 and the-outer surface of the cover 25, there is provided a gap 29 extending all the way around said spring core 24, The height of this gap corresponds to the desired height of the layer of foam material. Thus, the spring core24 is floatingly arranged, and this floating mounting may be realized by pins or similar spacer means (not shown in the drawings). The material to be foamed is then introduced into the closed mold composed of the sections 27 and 28 through one or more feeding passages 30 and is foamed directly around the spring core 24 so that a layer of foam material closed in itself forms the surface of the spring core. a

When the first foaming tests for mattresses with a spring core were carried out, it was found that during the foaming, the textile fabric which surrounds the spring core enters an intimate and solid connection with the foam material so that the air in the spring core will during the foaming operation be enclosed in an airtight manner with the result that an air core forms. This air core will during the foaming operation develop a counter pressure against the foam pressure during the foaming operation to such an extent that an undesired compression of the spring core will be prevented. Consequently, form-true foam bodies properly corresponding to the desired form are obtained in which the spring core is firmly embedded.

,FIG. 2 shows a further embodiment of a mattress with a preferred size ratio between the spring core 24a and the cover 32 of foam material. At the top and bottom side, the layer 32 of foam material has a thickness which is only slightly less than half the height of the spring core 24a. The lateral parts 33 of the foam material layer 32 on the other hand, are only slightly thicker than a fourth of the height of the spring core 240. These lateral parts 33, however, have a greater density and thus have an increased stiffness or rigidity. In the edges of the mattress, reinforcements 34 in the form of textile fabric or the like are embedded in the layer 32 of foam material so that the mattress will have form retaining edges. The entire layer 32 of indicated by the arrow 4, and which when looking down on the spring core 24a have an angular or corner shape. The springs are, in the transverse direction (arrow 4) of the spring core, arranged adjacent to each other in rows 5 whereas in longitudinal direction of the spring core (arrow 3) are arranged one after the other in rows 6, 7. The individual springs are interconnected by fine wires 8 10 extending in transverse direction (arrow 4) and furthermore interconnected by fine wires 11 13 extending in longitudinal direction (arrow 3).

As illustrated in FIG. 4, the outermost spring coils 14 of the springs 1 are located in planes which are parallel to the plane of the spring core. These outermost coils are formed by three legs 15 16 arranged at a right angle with regard to each other. The next two legs 18, 19 adjacent to the outermost spring coil 14 extend at an inclination with regard to the plane of the spring core. The then adjacent legs 20, 21 of the spring 1 are again located in a plane parallel to the plane of the spring core. The inclination of the legs 18, 19 is so selected that the distance of the legs 20, 21; 15, 16 which are plane parallel to the spring core will in the longitudinal direction of the spring 1 equal approximately the length of the legs 15, 16, 18, 19, 20 and 21. With the embodiment illustrated in the drawing, the legs 15, 16; 20, 21 are located in four superimposed planes parallel to each other.

In view of the rectangular cross-section of the springs in combination with the outermost coils thereof respectively located in a plane parallel to the plane of the spring core, there will after the foaming of the cover 32 be obtained a very high form stability of the spring core and,if desired, a firm connection between the cover 32 of the foam material and the spring core 24a. The two end legs 17 of each spring are inclined with regard to the center of the spring core so that the cover 32 of foam material or the cover 25 cannot be damaged.

As will be evident from FIG. 3, the springs 1 when seen from the top have a substantially trapezoidal shape while each two legs 15, 16; 20, 21 are forming a right angle with regard to each other and the other two oppositely located legs 18, 19 define with each other an angle of slightly less than 20 The springs l of the spring rows 6, 7 extending in the longitudinal direction (arrow 3) of the spring core are arranged in the respective rows 6, 7 in a position corresponding to each other. The springs 1 of the rows 6, 7 which extend in the longitudinal direction (arrow 3) and are adjacent to each other in the transverse direction (arrow 4) are offset with regard to each other by 90 in such a way that, for instance, the spring end legs 17 of said adjacent rows 6, 7 are ofiset to each other by 90. The springs of each spring row extending in the longitudinal direction (arrow 3) of the spring core are arranged in the same position, but are offset with regard to the springs of the adjacent spring row by 90. In this way, the legs parallel to the plane of the spring core and respectively pertaining to two adjacent spring rows are located directly adjacent to each other while the legs 15, 16 which are arranged along a straight line one behind the other are interconnected by fine wires 13 in such a way that according to FIGS. 3 and 4, always two fine wires 13 are arranged directly adjacent to each other. This brings about that the legs 15, 16 of the adjacent spring rows can in response to a load acting upon the spring move toward each other and thereby can support each other.

The fact that the fine wires will over the entire extension of the spring core enclose rectangulars of substantially identical sizes which respectively correspond to the plan view of two springs brings about that there will be obtained a very uniform structure and thereby a uniform spring effect and a uniform load distribution over the cover 32. The longitudinal central area of the spring core is reinforced by the fine wire 13 arranged in pairs adjacent to each other so that also in the central area a sufiicient force of the spring core will be assured. The asymmetry of the springs is balanced with regard to each other by the offset arrangement of the individual springs.

The springs l are so arranged that in the longitudinal direction of the spring core (arrow 3) and in the transverse direction thereof (arrow 4) always two legs 16, 20; 15, 16; 21, 20, are located along a straight line and plane parallel to the plane of the spring core one behind the other. The helical fine wires 8 13 are wound around these just-mentioned legs of the spring 1. Within the marginal area 2 of the spring core, the outermost windings 14 are interconnected by means of two fine wires 8, 9; 11, 12 pointing in the same direction whereby an additional reinforcement of the marginal area 2 of the spring core will be assured.

Instead of reinforcing the marginal area 2 of the spring core by means of two or more fine wires 8, 9; 11, 12, the marginal area 2 of the spring core may also be reinforced by one or more flat steel frames 22, as shown in FIG. 5. Such frame 22 is connected to the marginal springs located in the marginal area and is preferably embedded in the cover of foam material.

The ends 23 of the fine wires 8 13 are bent at a right angle and are wound around the legs of the corresponding springs 1, said legs forming the marginal area 2 of the spring core.

The soft foam may be so foamed upon the cover 25 of the spring core that it combines with the cover in such a way that this layer will have great strength, especially against wear. Between the spring core and the soft foam layer proper there is thus formed an intermediate layer which will assure a safe support on the spring core.

It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings, but also permits modifications, the invention being determined by the scope of the disclosure.

It is furthermore to be understood, that the method according to the invention is not limited to the making of mattresses, but also covers the making of upholstered bodies, such as seats for automobiles, and the like.

What we claim is:

l. A method of making an upholstered body having a core body comprising metallic springs, which includes the steps of enclosing said core body within the walls of a closed mold with space between the core body and mold walls on all sides, and introducing foaming material into said space between the core body and mold walls, completely filling said space with foamed material to surround said core body on all sides, so that the core body and air are enclosed within said foamed material and act to cushion said upholstered body.

2. A method of making an upholstered body having a core body comprising metallic springs, which includes the steps of covering the core body with sheet material, enclosing the covered core body within the walls of a closed mold with space between the core body and mold walls on all sides, and introducing a foaming material into said space between the core body and mold walls, completely filling said space with foamed material to surround said core body on all sides, so that the core body and air are enclosed within said foamed material and act to cushion said upholstered body.

3. A method of making an upholstered body as claimed in claim 2, which includes the step of lining the walls of the mold with a sheet material to form a cover for the foamed material of the upholstered body.

4. A method of making an upholstered body as claimed in claim 3, in which gas under pressure is applied to the mold to hold said sheet material lining the walls of the mold in place until the foaming material fills the space between the core body and walls and expels said gas.

5. A method of making an upholstered body having a core body comprising metallic springs, which includes the steps of covering the core body with textile material, enclosing the covered core body within the walls of a closed mold with space between the core body and mold walls on all sides, in-

cover as said foamed material enters into an intimate connection with said textile material, so that the core body and air within said cover are enclosed within said foamed material and act to cushion said upholstered body. 

2. A method of making an upholstered body having a core body comprising metallic springs, which includes the steps of covering the core body with sheet material, enclosing the covered core body within the walls of a closed mold with space between the core body and mold walls on all sides, and introducing a foaming material into said space between the core body and mold walls, completely filling said space with foamed material to surround said core body on all sides, so that the core body and air are enclosed within said foamed material and act to cushion said upholstered body.
 3. A method of making an upholstered body as claimed in claim 2, which includes the step of lining the walls of the mold with a sheet material to form a cover for the foamed material of the upholstered body.
 4. A method of making an upholstered body as claimed in claim 3, in which gas under pressure is applied to the mold to hold said sheet material lining the walls of the mold in place until the foaming material fills the space between the core body and walls and expels said gas.
 5. A method of making an upholstered body having a core body comprising metallic springs, which includes the steps of covering the core body with textile material, enclosing the covered core body within the walls of a closed mold with space between the core body and mold walls on all sides, introducing foaming material into said space between the core body and mold walls, completely filling said space with foamed material to surround said core body on all sides, the air within said textile material initially escaping under pressure of the foaming material and then being confined within said cover as said foamed material enters into an intimate connection with said textile material, so that the core body and air within said cover are enclosed within said foamed material and act to cushion said upholstered body. 